Ophthalmology - Neuro Ophthalmology - Reyes

November 4, 2017 | Author: anna_cabrera_6 | Category: Visual System, Nervous System, Neuroanatomy, Human Anatomy, Neurology
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Neurologic Ophthalmology Dr. Alberto

February 13, 2012 SIXTH BLOCK SY 2011 – 2012 NOTE: Some were taken from online sources. Please refer to the powerpoint prepared for pictures and some additional notes. Also, please browse on the assigned readings given to us by Doc Alberto  I. HISTORY History       

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Patient’s age, sex, race and occupation Hand dominance: patients with stroke affecting the visual pathway Symptom onset (e.g. acute, chronic, insidious) Duration Course of the condition (e.g. static, progressive, or relapsing and remitting) Lateralization or binocularity of visual deficits Associated features of the patient’s visual symptoms o Pain o Headache o Nausea o Vomiting o Weakness o Seizures Medical history o Trauma (e.g. motor vehicle accidents), and history of cancer o Past surgery, previous consults o Previous therapeutic intervention and the response to those treatments o Whenever feasible, personally review the patient’s CT scans or MRIs Family history o Optic neuropathies o Glaucoma o Multiple sclerosis o Unexplained blindness (one of the most common referrals to neurologic ophthalmology) o Diabetes Social history o Patient’s occupation o Alcoholism o Travel o Previous transfusions, the patient’s sexual habits, use of intravenous recreational drugs A complete history often defines the clinical problem and allows the examiner to proceed with a complete but focused neuro ophthalmic examination Unexplained visual loss (common in neuro-ophthalmic consult)

Chief Complaint Blurring of vision  Monocular, bilateral  Homonymous or heteronymous defect  Transien chronic or repetitive  Distance, near or both  Transient visual obscurations that last for seconds may be due to increased intracranial pressure  Painless unilateral visual loss that lasts several minutes may be embolic (amaurosis fugax)  Sudden-onset visual loss with little recovery o suggests ischemic event  Subacute visual loss associated with pain but with recovery of vision after several weeks or months o optic neuritis  Slowly progressive visual loss o Suggests compressive optic neuropathy  Visual loss with headache in an elderly patient o Suggests giant cell arteritis (not very common in the Philippines) Diplopia  Probably the next most common referral to neuro ophthalmology  Monocular or binocular, relative orientation of the separated images o If binocular, suspect a neurological condition o If monocular, consider possible error of refraction or a localized problem in the retina  Frequency, activities that enhance the diplopia  There may be added symptoms such as ptosis or known dysthyroidism  Monocular diplopia improves with pinhole – errors of refraction (EOR), optical aberrations of the media, retinal disorders that distort the fovea  Monocular diplopia that improves with blinking o Possible for patients with dry eye

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By Tintin

Binocular diplopia with horizontal separation that is worse in the distance suggests CN VI palsy Variability or worsening of the diplopia as the day progresses with associated ptosis suggests myasthenia gravis

II. PHYSICAL EXAMINATION Neuro-ophthalmic Examination 1. Best corrected visual acuity Using either a Snellen acuity chart at 20 ft. or a near card equivalent for each eye (OD = R eye; OS = L eye) 2. Pupil examination 3. Visual field examination 4. Extraocular motility examination 5. Fundoscopic examination Review of the Pupillary Responses Pupils: constriction and parasympathetic input  Please refer to Slide 2  Light stimulates photo receptors in the retina  Pupil motor fibers transmitted via the optic nerves; hemidecussation at the chiasm  Exit from the optic tracts (before the lateral geniculate body)  Enter the brainstem via the brachium of the superior colliculus  After synapsing in the pretectal area, fibers are distributed to the ipsilateral and contralateral Edinger Westphal nuclei  The efferent pupillary fibers travel via the third nerve to synapse in the ciliary ganglia after exiting the ciliary ganglion  Short ciliary nerves then go to the iris sphincter and ciliary body Pupils: dilation and sympathetic input  Please refer to Slide 3  Less well defined  Originates in the hypothalamus  Descends uncrossed, to the level of C8-T2  Exits from the spinal cord via the perivertebral sympathetic chain  Synapses in the superior cervical ganglion  Follows the carotid plexus to join the ophthalmic division of the trigeminal nerve  It reaches the ciliary body and the dilator of the iris, via the long ciliary nerves Examination of the Pupils 1. Note the size and shape in darkness and in light 2. Check for the light reflex in each eye individually 3. Look for an afferent pupillary defect (RAPD or Marcus Gunn Pupil): The Swinging Flash Light Test o Normal: stimulate the R eye  R pupil constricts  swing light to L eye  L eye appears to dilate momentarily then constricts due to light o Marcus Gunn pupil: stimulate the R eye  R pupil constricts  swing light to L eye  L pupil remains dilated (paradoxical dilatation)  (-) Direct reflex but you have a (+) consensual reflex The pupils must react to light in order to perform the test Not a test of the pupil per se – but we look at the pupil when we do the test Tests the optic nerve function 4. Check for the near reflex by bringing the patient’s own finger toward his nose 5. Recording the pupils examination Record the actual size of the pupil OD (right eye) and OS (left eye) Example: “pupils in darkness 8 mm OU (both eyes), in light 3 mm OD and 2.5 mm OS. Each pupil is briskly reactively to light. No relative afferent pupillary defect (no RAPD). Good near reflex.” RAPD: Rapid afferent pupillary defect  Please refer to Slide 4  Or Marcus-Gunn pupil  Unequal light conduction of the afferent visual pathway  Examine in the dim light with distant fixation  The lesion can be anywhere from the retina to the optic tract before the lateral geniculate body  Optic neuritis or ischemic causes

Clinical rules about Marcus-Gunn pupils  You never see APD with ocular media opacities (e.g. cataract)  You never see APD with functional amblyopia of childhood  An optic neuropathy of any cause will result in an APD, often disproportionate to the level of visual acuity  Bilateral APD’s do not exist o One functioning pathway is required to determine if an APD is present o If both afferent pathways are dysfunctional then pupil response is equal

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Light and near reactions are intact Anhidrosis (decreased sweating) on the affected side of the face Vs. ptosis associated with CN III lesions – more severe and with a dilated pupil A differential for acute pupil dilation with ptosis (a medical emergency)

Pupil pathology  Lesions of the parasympathetic system – dilated pupil (greater anisocoria in light)  Dilated pupil with other signs of acute motility disturbances and ptosis – think of an acute third nerve palsy – compression of the third nerve due to a posterior communicating artery aneurysm o If acute, think of PCA aneurysm  An isolated dilated pupil does not usually signify a CN III nerve palsy  Light-near dissociation can be seen in lesions in the midbrain  Light-near dissociation is used as a generic term that includes not only Argyll Robertson pupils  Argyll Robertson pupils are miotic pupils with irregular in shape  Tertiary syphilis is the most common cause of Argyll Robertson pupils o Not frequently seen anymore Dilated pupil associated with acute oculomotor nerve (CN III) palsy  Please refer to Slide 5  Anisocoria with acute onset of third-nerve palsy and associated with headache or trauma – neurosurgical emergency, especially if you have signs of o Complete or partial palsy o Complete or partial ptosis o Diplopia o (With or without pupil involvement)  Sudden onset of painful third-nerve palsy with pupil involvement and no history of trauma or vascular disease – intracranial aneurysm o Most common site is the posterior communicating artery Tonic pupil or Adie’s pupil  Please refer to Slides 6-8  Dilated pupil with very poor/no light reaction and tonic constriction to near and tonic redilation o Remember when we accommodate, part of the response is pupil constriction  Damage is post-ganglionic (ciliary ganglion)  The near response is also slow but discernable vs. the light response  Light-near dissociation: the dilated right pupil constricts slowly and progressively until it becomes slightly smaller than the simultaneously constricted left pupil  Supersensitivity of the sphincter muscle to pilocarpine Argyll Robertson pupil  Please refer to Slide 9  Pupils are small and irregular  They do not react to light but they accommodate (“prostitute’s pupil”)  Stigma of tabes dorsalis: slow demyelination of the sensory nerves in the dorsal columns of the spinal cord that carry information about proprioception, vibration, and discriminative touch  Diabetes mellitus and alcoholism can cause pseudo-ArgyllRobertson’s pupils  Not all light near dissociation is AR pupil!  VDRL and FTA  Incidence of syphilis: 0.20%  Incidence of gonorrhea: 1.03%  Incidence of Chlamydia: 1.48%  Cases are hardly seen already Horner’s syndrome  Please refer to Slide 10-11  Lesions of the sympathetic system cause a small pupil (increased anisocoria in darkness)  Ptosis  Slight elevation of the lower lid  Enophthalmos (the impression that the eye is sunken)  Miosis (constricted pupil) and dilation lag

Figure 1. Pharmacologic testing is used to confirm the diagnosis of Horner’s syndrome and to determine the location of the lesion in the sympathetic pupillary pathway.  

Cocaine test – 10% cocaine instilled will not dilate the eye with a sympathetic defect; normal eye dilates Hydroxyamphetamine test – dilation of a Horner’s eye means the lesion is preganglionic (before the superior cervical ganglion). No dilation lesion is postganglionic.

Pupil pathology  Pharmacologic blockade o Can occur due to accidental exposure of the iris to a dilating agent (e.g. Jimson weed; scopolamine patch, Atropine) o Test with pupillary constricting drug – Pilocarpine 1% - if no reaction – likely pharmacologic blockade Pupil anomalies Tonic pupil Acute thirdnerve palsy Pharmacologic dilation Horner’s syndrome Argyll Robertson pupils


Light reaction

Near reaction

(+) d (+) d

(-) or minimal (-)

(+) but slow (-)

(+) d



(+) c



(+) Small irreg



Visual Fields and Pathway  Localize a lesion in the visual sensory pathway  Visual fields testing by confrontation o Each eye is covered separately. Ask the patient to fixate on your nose and then you present fingers rapidly in all four quadrants of his vision while he counts the fingers o Hand-to-hand comparison when both hands are presented in the inferior field or the superior field. Ask the patient which he sees better o One can test the field with a red object and ask the patient if he/she sees both objects as red in both the superior and inferior fields o Double simultaneous stimulation. Once can test double simultaneous stimulation by having the patient fixating on the nose with both eyes open and by wiggling the fingers in the outside quadrants. However, this form of visual field testing is not adequate for the routine examination. Each eye must be tested separately.  Recording the visual field (Please refer to Slide 13) Ophthalmology – Neurologic Ophthalmology Page 2 of 4

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Confrontation test is difficult to use when trying to localize; better to use the automated visual field testing or perimetry Other ways of visual field testing o Tangent screen o Goldmann visual field perimetry o Automated perimetry  Uses a computer program and it determines your response.  When the patient sees the light, he presses and that records his response.  Repeated several times over a span of 40 minutes for both eyes. So this is very accurate. You are able to plot the visual defect much better

Figure 2. Automated perimetry.

Terms     

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There are types of fields produced Hemianopsia (hemianopia) implies partial blindness in the visual fields of one or both eyes, and not necessarily halfblindness as the etymology of the term may suggest Quadrantanopsia is a class of hemianopsia but confined to visual field quadrant(s). Scotoma is one or more islands of blindness within a seeing zone (e.g. the physiological blind spot) Homonymous implies correspondence and means (from ancient Greek) “with the same name.” This adjective can modify…: o Hemianopsia o Quadrantanopsia o Scotoma …and refers to: o The corresponding visual fields of the two eyes, either the right fields or the left fields (temporal and nasal’ fields) o The corresponding parts of the visual pathways (e.g. temporal and nasal’ hemiretinas – T and N’) Heteronymous implies a bilateral defect of the noncorresponding visual fields (seldom used) o By convention, a field defect is named for the field When referring to a homonymous hemianopsia, “right” or “left” signify either the right or the left half of the binocular visual field Altitudinal hemianopsia refers to a field defect above or below the equator with the blinded zone extending across the prime meridian (midline) At the optic chiasm, nasal fibers cross, temporal fibers do not.

Anatomy: visual field afferent system  Please refer to Slide 14  Retina  Optic disc  Optic nerve  Optic chiasm  Optic tract  Lateral geniculate body  Optic radiation  Occipital cortex  For more of visual field defects: Please refer to Slide 15 Homonymous hemianopsia  Please refer to Slide 16  Homonymous hemianopsia

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Post-chiasmal lesion On the side of the brain opposite the compromised half Is this a right or left homonymous hemianopsia? Lesion is on what side of the brain? Is there macular splitting or macular sparing? Macular splitting can occur in lesions both before or after the LGB (lateral geniculate body or nucleus). Macular sparing tends to occur with lesions beyond the LGB

Bitemporal hemianopsia  “Tunnel vision”  Sometimes, in glaucoma, when you have an isolated island of vision, they also refer that as “tunnel vision,” but the correct term is bitemporal hemianopsia  The signals for the temporal fields are carried by fibers from the nasal hemiretinas – the crossed fibers  The optic chiasm, where the crossed fibers (N + N’) lie close together, is implicated  Pituitary gland lesions

Extraocular Motility Third nerve disorder  Please refer to Slide 17  Usually associated with diplopia or ptosis  Dilated pupil, the ptosis on the same side  Ophthalmoplegia except for the LR and SO  Sudden onset of a third nerve palsy: - aneurysm?  Brainstem or midbrain infarction o Sudden onset with other neurologic findings such as ipsilateral third nerve paresis with contralateral hemiparesis (Weber’s syndrome)  Ipsilateral third nerve paresis with contralateral hemitremor – expanding mass in the temporal lobe because the third nerve caught between the edge of the tentorium cerebelli and the uncus of the temporal lobe in Uncal Herniation Syndrome  Cavernous sinus lesions and superior orbital fissure masses can also cause third nerve lesions  Isolated third nerve palsies (common in the clinics) o Might have diplopia, but pupils are still responsive o Usually a diagnosis of exclusion o Ischemic (from diabetes): DM neuropathy  Most common very it’s a very long nerve inside the brain and is therefore prone to ischemic assaults o Aneurysmal compression (look for pupil enlargement)  Prone for this also because of its length o Trauma  First one to be affected usually due to its length o Tumor (check for aberrant regeneration) o Infection o Inflammation o Idiopathic The III nerve pathway  The oculomotor nerve arises from the anterior aspect of midbrain  There are two nuclei for the oculomotor nerve: o Oculomotor nucleus originates at the level of the superior colliculus  Ciliary muscle, and all extraocular muscles except for SO and LR o The Edinger-Westphal nucleus supplies parasympathetic fibers  Ciliary ganglion, and thus controls pupil constriction  On emerging from the brain, the nerve is invested with a sheath of pia mater, and enclosed in a prolongation from the arachnoid  Passes between the superior cerebellar and posterior cerebral arteries  Pierces the dura mater in front of and lateral to the posterior clinoid process, passing between the free and attached borders of the tentorium cerebelli  Runs along the lateral wall of the cavernous sinus o Receiving filaments from the cavernous plexus of the sympathetic, and a communicating branch from the ophthalmic division of the trigeminal  It then divides into two branches, which enter the orbit through the superior orbital fissure, between the two heads of the lateral rectus  Here the nerve is placed below the trochlear nerve and the frontal and lacrimal branches of the ophthalmic nerve, while the nasociliary nerve is placed between its two rami: o Superior branch of oculomotor nerve o Inferior branch of oculomotor nerve Ophthalmology – Neurologic Ophthalmology Page 3 of 4

Fourth nerve pathway  Please refer to Slide 18  Nucleus: in the periaqueductial gray  It emerges on the dorsal surface of the brainstem and passes around it  Cavernous sinus – superior orbital fissure  Supplies the superior oblique muscles (depressor in adduction; rotator) o Therefore, CN 4 lesion may also cause diplopia  Longest course of any cranial nerve in the subarachnoid space o So it also tends to be involved in trauma  Basically all things that affect the CN III may also affect the CN IV. o The only difference is that if it’s a CN IV lesion, they can still have eye movements and they often complain of vertical diplopia Fourth nerve palsies  Patients complain of vertical diplopia  Trauma – long and very delicate nerve  Isolated IV palsies o Trauma: most common, even by small head trauma o Ischemic o Masses (along the clivus) Sixth nerve pathway  The abducens nerve nucleus lies underneath the fourth ventricle  Leaves the brainstem at the pontomedullary junction  Runs in the subarachnoid space along the base of the pons  Cavernous sinus – superior orbital fissure Sixth nerve palsy  Probably the least commonly affected but may still cause diplopia since it innervates the lateral rectus muscle  Isolated sixth nerve palsies have no localizing value  If they are associated with other neurologic signs such as fifth nerve palsy, seventh nerve palsy, or eighth nerve palsy, they may be of localizing value  Chronic sixth nerve palsies should be evaluated  Isolated VI nerve palsy: o Idiopathic o Ischemic o Traumatic o Inflammation o Tumor o Cavernous sinus thrombosis Fundoscopic Examination Papilledema (emphasized!)  Non-inflammatory passive swelling of the optic disc, produced by raised intracranial tension (ICT)  Papilledema vs. disc edema o Papilledema: raised ICP o Disc edema: no ICP problem  Interrupted axoplasmic flow in the optic nerve due to elevated CSF pressure in the subarachnoid space causing venous congestion o In disc edema, the interrupted axoplasmic flow in the optic nerve due to flow of blood in the optic nerve itself wherein you have optic neuropathies Optic atrophy/optic neuropathy  Please refer to Slides 25-26  Death of the retinal ganglion cell axons that comprise the optic nerve  Pale optic nerve on fundoscopy  End stage of optic nerve disease that arises from myriad causes of optic nerve damage anywhere along the path from the retina to the lateral geniculate  Results in vision loss END OF TRANS. Thank you Karen, Crissy, Mia and FioFioFio 

Ophthalmology – Neurologic Ophthalmology Page 4 of 4

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